Trilobal Fibers Research Articles

On the filtration performance of dust-loaded trilobal fibers

This paper is prepared to shed some light on the filtration performance of fibers with trilobal cross-section in comparison to their circular counterparts when loaded with aerosol particles. A trilobal geometry consisting of three overlapping elliptical lobes with major and minor diameters of 8 and 4μm, and a particle diameter range of 0.125–2μm are considered as representative examples of fibers and particles of a common aerosol filtration application. The results reported in this paper are obtained using micro- and macroscale simulation methods that we previously developed for modeling unsteady-state dust-cake formation inside and outside fibrous filters. Different flow velocities are considered to discuss performance of trilobal fibers under different particle capture regimes. For the range of particle and fiber diameters considered, the trilobal fibers are found to outperform their circular counterparts only when the particles are highly inertial, and only if the orientation of the trilobal cross-section with respect to the incoming flow is such that one of the grooves of the fiber faces the flow with a normal angle. This is in agreement with our previous simulations of clean trilobal fibers. In the case of low inertial particles, trilobal fibers were found to exhibit a higher efficiency with loading but at the expense of a significantly higher pressure drop. With the lack of perfect control over how the grooves will be oriented in a fibrous filter, one may conjecture that, other parameters being constant, the probability of an aerosol filter comprised of trilobal fibers performing better than its counterpart made of circular fibers is not very high. We also studied the effects of the through-plane orientation of the trilobal fibers on their performance relative to their circular counterpart. Similar conclusions were drawn from the latter simulations.

Study on On the Cross-Sectional Shape Change of the Profiled Fiber along the Spinning Path in Melt Spinning

The cross-sectional shape of profiled fibers has made obvious influence on fibers physical properties. The fiber profiled factor is an index used to estimate the deformation degree of profiled fibers. Based on the equations of melt-spinning dynamics and deformation, a numerical simulation program for calculating the fiber profiled factor along the spinning path was developed. A numerical simulation for calculating the fiber profiled factor along the spinning path of trilobal fibers in the PET melt spinning was performed. The simulation result graph of the fiber profiled factor along the spinning path is close to the final average fiber profiled factor measured in the spinning experiment under the same condition.

Effect of polypropylene fiber cross sectional shapes on some structural/mechanical fiber properties and compressibility behaviour of plain knitted fabrics

Synthetic fibers are generally produced with circular cross sectional shapes. Other cross sectional shaped fibers such as trilobal, triangular, hollow and pentagonal fibers are also produced to improve some properties of fibers and fabrics such as lustre, handle, wicking rate, strength, stiffness and bulkiness. In this research we aimed to investigate compressional behaviours of fabrics knitted from polypropylene fibers having three different cross sectional shapes; namely circular, trilobal and triangular. Morphological, structural and mechanical properties of produced fibers were evaluated by using scanning electron microscopy, X-ray diffractometry, differential scanning calorimetry and tensile tester, respectively. In terms of structural and mechanical properties, no significant differences were found related to fiber cross sectional shapes. Then, plain knitted farbrics were produced and compressional properties of these fabrics were investigated. Fabrics knitted from trilobal fibers showed the highest compressibility properties and it is followed by fabrics which are produced from triangular and circular fibers.

Analytical expressions for predicting performance of aerosol filtration media made up of trilobal fibers

Despite the widespread use of fibrous filtration media made up of trilobal fibers (referred to as trilobal media here), no mathematical formulations have yet been developed to predict their collection efficiency or pressure drop. In this study, we model the cross-section of a trilobal fiber with three overlapping ellipses separated from one another by a 120° transformation. We generate 2-D models representing the internal structure of trilobal filters having fibers with different dimensions and aspect ratios, and used them to predict pressure drop and collection efficiency of trilobal filter media. This information is then utilized to define an equivalent medium with circular fibers for each trilobal filter. Our results indicate that the circumscribed circle of a trilobal fiber can serve as an equivalent circular diameter, and therefore be used in the existing empirical/semi-empirical correlations that have previously been developed for predicting performance of filters with circular fibers. We have also proposed easy-to-use expressions that can be used with our equivalent circumscribed diameters for calculating the pressure drop of trilobal media.

Effects of Spinning Conditions on Shape Changes of Trilobal-shaped Fibers

The effects of spinning conditions on shape changes in the trilobal-shaped fiber spinning of poly(ethylene terephthalate) (PET) and polypropylene (PP) fibers were studied with a focus on spinning parameters such as mass flow rate, spinning temperature and take-up. Extrudate at the die-swell points along the spinline was obtained to investigate shape change. Extrudate shape at the die-swell points affected the shape factor of as-spun PP fibers. Surface tension affected the fiber cross-section of the PET trilobal fibers, whereas die swell was more important in the PP trilobal fibers. The shape factor of the PP trilobal fibers decreased with increasing mass flow rate, spinning temperature and take-up speed, whereas that of the PET trilobal fibers increased with increasing mass flow rate and take-up speed.

Observations of Soiling of Nylon 66 Carpet Fibers

Soiling of nylon 66 carpets was studied to investigate the effect of spin finishes with and without fluorocarbons finishes; and, in addition, the use of a secondary extraction process was examined to determine the effect of removing residual spin finish oils. Two types of residential carpet of intimate blend trilobal fibers with two modification ratios were evaluated: one had fluorcarbons in the spin finish with an additional topical mill-applied fluorocarbon. The second carpet had no fluorocarbons in the spin finish, but had a topical mill-applied fluorocarbon finish so that both carpets had a target of 250 to 300 ppm fluorine. Acetone extraction was used to remove the spin finishes from the carpets. Both carpets with and without extraction were soiled with particulate soil in the laboratory. Visual ratings and color difference measurements indicated more soiling on the carpets that had been extracted. Fluorine analysis showed that fluorcarbons were removed from both carpet types with the acetone extraction. Electron microscopy indicated the deposition of soil in the V-groove of the filaments with the higher modification ratio. Furthermore, fiber surfaces near the face of the carpet exhibited higher levels of soil than surfaces located near the carpet backing.

Preparation and characterization of trilobal activated carbon fibers

The objective of this research was to evaluate the effectiveness of several different methods for controlling the pore size and pore size distribution in activated carbon fibers. Variables studied included fiber shape, activation time, and the addition of small amounts of silver nitrate. Pure isotropic pitch and the same isotropic pitch containing 1 wt.% silver were melt spun to form fibers with round and trilobal cross sections. These fibers were then stabilized, carbonized, and activated in carbon dioxide. Field emission scanning electron microscopy (FE SEM), electron dispersive spectra (EDS), and wavelength dispersive spectra (WDS) were used to monitor the size and distribution of the silver particles in the fibers before and after activation. Each of these analyses showed that the distribution of silver particles was extremely uniform before and after activation. The fibers were also weighed before and after activation to determine the percent burn-off. The BET specific surface areas of the activated fibers were determined from N 2 adsorption isotherms measured at −196 °C. The results showed that round and trilobal fibers with equivalent cross-sectional areas yielded similar burn-off values and specific surface areas after activation. Also, activation rates were found to be independent of CO 2 flow rate. The porosity of the activated fibers depended on the total time of activation and the cross-sectional area of fibers. The N 2 adsorption measurements showed that the activated fibers had extremely high specific surface areas (greater than 3000 m 2/g) and high degrees of meso- and macro-porosity. FE SEM was also used to investigate surface texture and size of pore openings on the surfaces of the activated fibers. The photos showed that silver particles generated surface macro- and mesopores, in agreement with the inferences from N 2 adsorption measurements.

Determining Polyester Fiber and Microfiber Structure by Iodine Sorption

The characterization of polyester fiber structure is classically founded on several physicochemical techniques. One of the most common is iodine sorption, and we have modified this technique by increasing its capacity of analyze. With our modification, it is possible to distinguish various fibers without ambiguity. We use this new technique to characterize three polyester fibers: a microfiber, a 14 μm circular fiber, and a trilobal fiber. Virgin fibers of each type are divided into batches; each batch is subjected to heat setting in a vapor medium at a specific temperature and then tested. This procedure allows follow-up of the transformation of the fiber structure. Such an evolution provides information on the interactions of macromolecular chains. The different tests show that the polymer of the microfiber has a very particular organization, which mixes great accessibility with a significant rate of crystallinity. The sorption curves of iodine indicate that the trilobal fibers have an overall structure that is less differentiated than the other fibers.